A. Field of the Invention
The present invention pertains generally to conflation, and more particularly to the matching of nodes of spatial data from different data sources.
B. Description of the Background
Data can be represented spatially to provide a format for pictorially displaying that data. The displayed data may take the form of a map, a graph, charts, holograms, and other various types of two- and three-dimensional representations. For example, the U.S. government provides vector data (source data) that is known as xe2x80x9cTIGERxe2x80x9d, data that is representative of maps that cover the entire United States. This data indicates roads and other geographical landmarks, as well as what is referred to as xe2x80x9cattribute dataxe2x80x9d. Attribute data is located at the nodes between the vectors of the source data, and provides information such as street names and addresses, zoning, school districts, average home prices, average income, and various other demographic data that is associated with the particular location of that node. Of course, this information is valuable information to have available when looking at a particular geographical area.
One of the problems, however, is that typically the source data is faulty in some respects. For example, because of the way the data was obtained, it may not be spatially correct. There may be problems with scaling, skewing, offset, rotation, and other similar problems. Typically, these distortions are not systematic distortions that can be corrected in a systematic fashion. For example, in one portion of a map rotational distortion may be present, and another portion of the map may include an offset distortion. This results sometimes from the manner in which the data was collected, such as mistakes in surveying and other similar problems. Furthermore, the source data is typically not updated regularly, so that it does not include changes that have occurred. For example, source data may typically not include entire housing subdivisions or associated roads in newly-developed areas. This is the result of the fact that the source data from the government may not be updated for a number of years. It is therefore desirable to have information that is updated on a prompt and regular basis and that is spatially correct.
Digitized data, such as that provided by photographing land areas from high altitude airplanes and space satellites is capable of providing spatially correct data that can be promptly and periodically updated. This data can also be provided in a vector format such as the source data. However, digitized data that is provided in this fashion does not include accompanying attribute data, such as the attribute data provided with source data from the government.
Hence, it would be desirable to have data that is spatially correct and also includes associated attribute data which has not been provided previously with spatially correct sources of digitized data. More generally, it would be desirable to have a process for automatically tying a node from one data source to a corresponding node of a similar data source.
The present invention overcomes the disadvantages and limitations of the prior art by providing a system for matching nodes from separate data sources.
The present invention may therefore comprise a process of tying a selected node of a first data source to a corresponding node of a second data source comprising the steps of generating trace coordinates between the selected node and secondary nodes associated with the selected node, generating trace coordinates between potential corresponding nodes of the second data source and secondary nodes associated with the potential corresponding nodes, generating a fourier descriptor of the trace coordinates associated with the selected node, generating fourier descriptors of the trace coordinates associated with the potential corresponding nodes, comparing the fourier descriptors of the trace coordinates associated with the selected node with the fourier descriptors of the trace coordinates associated with the potential corresponding nodes to eliminate nonrelevant potential corresponding nodes of the potential corresponding nodes, tying the selected node to a single remaining node of the potential corresponding nodes that corresponds to the corresponding node.
The present invention may also comprise a computer system that is programmed to tie a selected node of a first data source to a corresponding node of a second data source by performing at least the steps of generating trace coordinates between the selected node and secondary nodes associated with the selected node; generating trace coordinates between potential corresponding nodes of the second data source and secondary nodes associated with the potential corresponding nodes, generating a fourier descriptor of the trace coordinates associated with the selected node, generating fourier descriptors of the trace coordinates associated with the potential corresponding nodes, comparing the fourier descriptors of the trace coordinates associated with the selected node with the fourier descriptors of the trace coordinates associated with the potential corresponding nodes to eliminate nonrelevant potential corresponding nodes of the potential corresponding nodes, tying the selected node to a single remaining node of the potential corresponding nodes that corresponds to the corresponding node.
The present invention may also comprise a computer-readable medium that contains program code that is capable of causing a computer to perform a process of tying a selected node of a first data source to a corresponding node of a second data source in accordance with the steps comprising generating trace coordinates between the selected node and secondary nodes associated with the selected node, generating trace coordinates between potential corresponding nodes of the second data source and secondary nodes associated with the potential corresponding nodes, generating a fourier descriptor of the trace coordinates associated with the selected node, generating fourier descriptors of the trace coordinates associated with the potential corresponding nodes, comparing the fourier descriptors of the trace coordinates associated with the selected node with the fourier descriptors of the trace coordinates associated with the potential corresponding nodes to eliminate nonrelevant potential corresponding nodes of the potential corresponding nodes, tying the selected node to a single remaining node of the potential corresponding nodes that corresponds to the corresponding node.
The present invention may also comprise a computer system that is programmed to tie a selected node of a first data source to a corresponding node of a second data source comprising means for generating trace coordinates between the selected node and secondary nodes associated with the selected node, means for generating trace coordinates between potential corresponding nodes of the second data source and secondary nodes associated with the potential corresponding nodes, means for generating a fourier descriptor of the trace coordinates associated with the selected node, means for generating fourier descriptors of the trace coordinates associated with the potential corresponding nodes, means for comparing the fourier descriptors of the trace coordinates associated with the selected node with the fourier descriptors of the trace coordinates associated with the potential corresponding nodes to eliminate nonrelevant potential corresponding nodes of the potential corresponding nodes, means for tying the selected node to a single remaining node of the potential corresponding nodes that corresponds to the corresponding node.
The advantages of the present invention are that corresponding nodes from a first source of data such as a source of digitized data can be tied to corresponding nodes of a second data source such as the source data that is provided by the government. In this manner, the spatially correct data can access the attribute data at the corresponding nodes of the source data to provide a system in which a spatially accurate and updated data source can be provided together with the accompanying attribute data. Additionally, the present invention utilizes an exclusion technique that is highly accurate to ensure that nodes are matched with a high degree of accuracy. This allows the matched nodes to be utilized for various purposes in addition to providing tie points between nodes, including conflation and other beneficial functions.